To understand how your breast cancer is likely to behave and which treatments are most likely to stop it, your doctors will identify several traits of your cancer when you are diagnosed or soon after.
- The type of breast cancer you have
- The grade of your breast cancer
- Whether your cancer is hormone-receptor positive
- Whether your cancer is HER2 positive
- The size of your tumor and whether it has spread (the stage of your cancer)
Your team at Seattle Cancer Care Alliance (SCCA) treats every type, grade and stage of breast cancer, using their deep experience to select and combine treatments to get the best possible results in your individual situation.
Breast cancers fall into these two main types:
- In situ breast cancer: Cancer that’s only in the milk ducts and lobules (milk-producing glands). In situ breast cancer is also called noninvasive breast cancer.
- Invasive breast cancer: Cancer that can start in the ducts or lobules but then spreads into surrounding breast tissue. It may eventually become metastatic, meaning it spreads to other organs, like the bones or lungs. Invasive breast cancer is also called infiltrating breast cancer.
In Situ Breast Cancer
Ductal carcinoma in situ (DCIS) is the most common noninvasive breast cancer. It is early-stage cancer confined to the milk ducts. Usually it causes no physical signs or symptoms and is detected by a screening mammogram.
Many women with DCIS can be cured by removing the tissue that contains the tumor. Left untreated, DCIS can become invasive cancer.
Invasive Breast Cancer
These are the most common types of invasive breast cancer.
- Invasive ductal carcinoma (IDC): IDC begins in a duct in the breast and breaks through into the surrounding fatty tissue of the breast. From there, IDC can spread to other parts of the body through the bloodstream or lymph. About 80 percent of invasive breast cancers are invasive ductal carcinomas, also called infiltrating ductal carcinomas.
- Invasive lobular carcinoma (ILC): ILC starts in the lobules and, like IDC, can spread to other parts of the body. It is also called infiltrating lobular carcinoma. This is the second most common type of invasive breast cancer.
- Inflammatory breast cancer (IBC): Only about 1 to 3 percent of women with breast cancer have IBC. This rare cancer may begin in either the ducts or the lobules. It is aggressive and progresses rapidly. In its early stages, IBC can be mistaken for infection because the symptoms are similar. Most infections will respond to antibiotics, but inflammatory breast cancer will not.
Other rare types of breast cancer include Paget’s disease of the nipple and phyllodes tumors.
The grade of an invasive breast cancer refers to how closely the cancer cells resemble normal breast cells under a microscope. Determining the grade is part of your biopsy.
- A lower number usually means a slower-growing cancer that is less likely to spread.
- A higher number usually means a faster-growing cancer that is more likely to spread.
There are three grades.
- Grade 1 (well differentiated): The cells in these cancers are relatively less abnormal looking. They do not appear to be growing rapidly.
- Grade 2 (moderately differentiated): The cancer cells are somewhat more abnormal.
- Grade 3 (poorly differentiated): These cancer cells look the most abnormal. They tend to grow and spread more aggressively.
The grade of a breast cancer is different from the stage. Stage is based on where the cancer has spread. Read about breast cancer stages.
Your care team will try to determine other traits of your breast cancer when they check the sample of tissue removed during your biopsy or a sample taken when your entire tumor is removed surgically.
Specifically, they will be looking for these two traits:
- Hormone-receptor status: Most women with breast cancer have hormone-receptor positive (HR+) disease. This means their cancer cells have one or both of these:
- Receptors where estrogen can attach (estrogen-receptor positive, or ER+, disease)
- Receptors where progesterone can attach (progesterone-receptor positive, or PR+, disease)
Most women have both types of receptors. If your cancer is HR+, this helps doctors predict that your cancer will respond to hormonal therapy.
- HER2/neu status: Some women with breast cancer have HER2-positive disease. This means their cancer cells make too much of a protein called HER2/neu, which indicates that the cancer may be more aggressive.
If your cancer is HER2 positive, this helps doctors predict that your cancer will respond to certain targeted biological therapies.
Triple-Negative Breast Cancer
The term “triple-negative breast cancer” refers to breast cancers that are:
- Not estrogen-receptor positive
- Not progesterone-receptor positive
- Not HER2 positive
What Does This Mean for My Treatment?
The comprehensive treatment plan that your SCCA breast cancer team recommends for you will depend on the type, grade and stage of your cancer, as well as your hormone-receptor and HER2/neu status. Learn more about your treatment options.